Validation of the renal risk score for antineutrophil cytoplasmic antibody-associated glomerulonephritis in a Chinese population

Abstract

Introduction: In 2018, a renal risk score of antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (AAGN) based on estimated glomerular filtration rate (eGFR), normal glomeruli, and tubular atrophy/interstitial fibrosis (TA/IF) was proposed to predict renal outcomes. We aimed to evaluate this renal risk score in a myeloperoxidase (MPO)-ANCA predominant population in Northeast China.

Methods: We retrospectively analyzed the clinicopathologic data of 65 patients biopsy-proven from a Chinese medical center. Each patient was assessed by eGFR, normal glomeruli, and TA/IF, and the renal outcome was evaluated using the renal risk score.

Results: In our study, 95.4% of patients were ANCA positive (78.5% MPO-ANCA positive and 16.9% proteinase 3-ANCA positive). The average follow-up period was 14.3 months. Thirty-four patients (52.3%) reached end-stage renal disease (ESRD). Based on the renal risk score, 8 (12.3%), 31 (47.7%), and 26 (40%) patients were divided into the low-risk, medium-risk, and high-risk groups, respectively. Kaplan-Meier survival curves revealed the high-risk group had worse renal outcomes than the low-risk group (p<0.01) and the medium-risk group (p<0.01), but the renal outcome did not differ between the low-risk and medium-risk groups (p>0.017). Similar results were obtained by the competitive survival analysis. The AUC for 3-year overall ESRD predictions was 0.845. In the regression analysis, the renal risk score was a favorable predictor for the development of ESRD (HR 3.13, 95%CI 1.58-6.19, p=0.001).

Conclusion: The renal risk score is a preferred index that can predict ESRD in Chinese AAGN patients, especially in the high-risk group with worse renal outcomes. Key Points • The eGFR and percentage of normal glomeruli were valuable predictors of renal outcome, whereas TA/IF was not. • We confirmed the renal risk score is a preferred index that can predict ESRD in Chinese AAGN patients. • Based on the renal risk score, the high-risk group had worse renal outcomes than the low-risk group and the medium-risk group.

Keywords: ANCA-associated glomerulonephritis; Clinicopathological manifestation; Outcome; The renal risk score.